Conventionally, there are different approaches to provide semiconductor chips of integrated circuits with contact areas. The basic technique is to provide them on the surface of the semiconductor chip as a metal area that is connected by conducting lines with the integrated circuit.
For contacting several semiconductor chips arranged in the stack, it is well known using electrical feed-throughs inside the bulk material to connect the circuitries of the different semiconductor chips via contact pads from the top surface of a semiconductor chip to the bottom surface. The bottom face is also the interface to contact pads of a second chip that adjoins the bottom surface of the first chip with a top face. This approach, however, is disadvantageous since the second semiconductor chip comprises devices or electronic circuits buried underneath the contact pads on the top surface.
In another approach electrical wires are fabricated around the rim of each semiconductor chip of a stack, either along its side face or through a carrier in which the chip is embedded. U.S. Pat. No. 5,656,553 discloses such a stack and the fabrication method for a monolithic electronic module comprising a plurality of stacked planar extending arrays of integrated circuit chips. The fabrication method includes dicing a wafer of integrated circuit chips into a plurality of arrays of integrated circuit chips. The arrays of the integrated circuit chips are then stacked to form an electronic module. A metallization pattern is deposited on a side face of the electronic module to interconnect the various arrays of the integrated circuit chips. This side surface metallization is only used for connecting the semiconductor chips of the stack to each other. This method requires dicing of a wafer into chips in order to continue processing of the wires and other packaging steps, which is typically less cost-effective than a batch fabrication at wafer scale.